This invention relates generally to thrust bearings and, more particularly, to thrust races used in thrust bearings with needle rollers.
Thrust bearings with needle rollers are in general use in transmissions and similar devices to support axial loads between components. For example, such thrust bearings are used in automotive torque converters to position and support a stator. Examples of such thrust bearings with needle rollers are illustrated in FIGS. 1–4. FIG. 1 illustrates a thrust bearing 10 with needle rollers 12 retained within a bearing cage 14 and in rolling contact with raceways of an inner thrust race 16 and an outer thrust race 18 that include inner and outer lips 20 and 22, respectively, that may be used for piloting of the bearing cage 14.
FIGS. 2 and 3 illustrate a similar thrust bearing 24 with needle rollers 26 retained within a bearing cage 28 and in rolling contact with raceways of an inner thrust race 30 and an outer thrust race 32 that include inner and outer lips 34 and 36 that may be used for piloting of the bearing cage 28. To retain the inner and outer thrust races 30 and 32 and the bearing cage 28 together as an assembly, the inner and outer lips 34 and 36 have staked portions 38 and 40 extending radially outwardly and radially inwardly, respectively, over the bearing cage 28. In other thrust bearings, not illustrated, in place of the staked portions 38 and 40, the inner and outer lips may be curled along a full 360 degree circumference to retain the thrust races and the bearing cage together.
With such thrust bearings, the inner and outer thrust races must be made of bearing quality material, typically high carbon steel, to provide high quality raceways, and must be finished with a good wear surface for the needle rollers and must be thick enough to carry the high loads under the needle rollers. Because of the limited ductility of the material, the forming of staked portions 40, or similarly curled portions, is difficult and at a risk of fracturing the thrust races. In addition, the bearing quality material makes the thrust bearing expensive. FIG. 4 illustrates that an angled band 42 may be mounted over an outer thrust race 44, that is similar in function to outer thrust race 18 of FIG. 1, to overcome some of these difficulties.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.